+40 Let's expand this. First, we need to know the FOIL (First, Outside, Inside, Last) method. Because both 2x-9 and 7x+4 are binomials (Because they are a sum of two monomials), to expand this, we need to multiply the First ones of both binomials (in this case 2x and 7x), then the Outside (Which means the First one of the first and Second one of the second binomial, so in this case 2x and 4), Inside (Opposite of inside, -9 and 7x in this case)*
* Warning: Be careful for the minus signs! when there is a minus before the term/constant value, you have to also count that as well when doing it. So it's not multiplying 9 and 7x!
...and finally the Last (The last one of both binomials, -9 and 4 in this case). so...
| X | 7x | 4 |
| 2x | 14\(x^2\) | 8x |
| -9 | -63x | -36 |
So, if you simplify the like terms (the xs), you get (2x-9)(7x+4)=\(14x^2-55x-36.\)
